Lighting member, lighting device, and method for installing lighting member

ABSTRACT

A lighting film ( 1 ) includes a first base material ( 2 ), a plurality of lighting portions ( 3 ), and a void portion ( 9 ), and if a virtual straight line (F) that passes through a point (C), at which any one light ray of light entering the lighting portion ( 3 ) is incident on a reflective surface, and is orthogonal to a first surface ( 2   a ) of the first base material ( 2 ) marks a boundary between two spaces, a space with the light ray incident on the point (C) of the two spaces is labeled as a first space (S 1 ), and a space without the light ray incident on the point (C) is labeled as a second space (S 2 ), the lighting film ( 1 ) has a function of decreasing intensity of light traveling toward the second space (S 2 ) of light emitted from the first base material ( 2 ) or the lighting portion ( 3 ).

The present application is a continuation application of U.S. patentapplication Ser. No. 15/027,878, filed on Apr. 7, 2016, which is theU.S. national phase of International Application No. PCT/JP2014/077533filed Oct. 16, 2014, which designated the U.S. and claims priority toJapanese Patent Application No. 2013-216496 filed in Japan on Oct. 17,2013. The entire disclosure of such parent application is incorporatedherein by reference.

TECHNICAL FIELD

The present invention relates to a lighting member, a lighting device,and a method for installing the lighting member.

BACKGROUND ART

A lighting film for letting sunlight into a room through, for example, awindow of a building is proposed in PTL 1. In the lighting film, aplurality of unit prisms and flat surfaces are formed on one surface ofan optically transparent support. Sunlight is let into a room throughthe unit prisms.

In the case of the above-described lighting film, however, light afterpassage through the lighting film may reach eyes of a person present ina room due to the effect of, for example, periodic motion of the sun.The light may cause glare, and the person in the room may feeldiscomfort. PTL 2 discloses a solar radiation shading control devicewhich adjusts the opening degree of a blind on the basis of an indexobtained from a particular mathematical formula for predicting glaresuch that the index has a value, at which glare does not causediscomfort.

CITATION LIST Patent Literature

PTL 1: Japanese Unexamined Patent Application Publication No. 2008-40021

PTL 2: Japanese Unexamined Patent Application Publication No.2007-120090

SUMMARY OF INVENTION Technical Problem

The solar radiation shading control device in PTL 2 includes a blind asshading means and suppresses glare by mechanically adjusting the openingdegree of the blind. The device thus suffers from the problem of highdevice cost.

One aspect of the present invention has been made to solve theabove-described problem, and one object thereof is to provide a lightingmember, a lighting device, and a method for installing the lightingmember capable of inexpensively suppressing glare.

Solution to Problem

In order to attain the above-described object, a lighting memberaccording to one aspect of the present invention includes a first basematerial having optical transparency, a plurality of lighting portionshaving optical transparency which are provided on a first surface of thefirst base material, and a void portion which is provided between theplurality of lighting portions, part of a side surface of the lightingportion in contact with the void portion functions as a reflectivesurface which reflects light entering the lighting portion, and if avirtual straight line F that passes through a point C, at which any onelight beam of the light entering the lighting portion is incident on thereflective surface, and is orthogonal to the first surface of the firstbase material marks a boundary between two spaces, a space with thelight beam incident on the point C of the two spaces is labeled as afirst space, and a space without the light beam incident on the point Cis labeled as a second space, the lighting member has a function ofdecreasing intensity of light traveling toward the second space of lightemitted from the first base material or the lighting portion.

In the lighting member according to the one aspect of the presentinvention, the function may be a function of scattering the lighttraveling toward the second space.

In the lighting member according to the one aspect of the presentinvention, the function may be an anisotropic scattering function ofcausing more scattering in a plane along a main extending direction ofthe side surface of the lighting portion functioning as the reflectivesurface than scattering in a different plane.

In the lighting member according to the one aspect of the presentinvention, the function may be a function of selectively scattering thelight traveling toward the second space.

In the lighting member according to the one aspect of the presentinvention, the first base material or the lighting portion may havelight scattering ability.

The lighting member according to the one aspect of the present inventionmay further include a second base material which is provided on anopposite side of the lighting portions from the first base material, anda bonding layer which bonds the lighting portions and the second basematerial together, and the second base material or the bonding layer mayhave light scattering ability.

In the lighting member according to the one aspect of the presentinvention, the first base material or a light emitting side of thelighting portion may include a light attenuating member which decreasesintensity of the light traveling toward the second space.

In the lighting member according to the one aspect of the presentinvention, the light attenuating member may be a light reflecting memberwhich reflects the light traveling toward the second space.

In the lighting member according to the one aspect of the presentinvention, the light attenuating member may be a light absorbing memberwhich absorbs the light traveling toward the second space.

A lighting device according to one aspect of the present inventionincludes a lighting member and a light attenuating member, the lightingmember includes a first base material having optical transparency, aplurality of lighting portions having optical transparency which areprovided on a first surface of the first base material, and a voidportion which is provided between the plurality of lighting portions,part of a side surface of the lighting portion in contact with the voidportion functions as a reflective surface which reflects light enteringthe lighting portion, and if a virtual straight line F that passesthrough a point C, at which any one light beam of the light entering thelighting portion is incident on the reflective surface, and isorthogonal to the first surface of the first base material marks aboundary between two spaces, a space with the light beam incident on thepoint C of the two spaces is labeled as a first space, and a spacewithout the light beam incident on the point C is labeled as a secondspace, the light attenuating member has a function of decreasingintensity of light traveling toward the second space of light emittedfrom the first base material or the lighting portion.

A method for installing a lighting member according to one aspect of thepresent invention, the lighting member including a first base materialhaving optical transparency, a plurality of lighting portions havingoptical transparency which are provided on a first surface of the firstbase material, and a void portion which is provided between theplurality of lighting portions, part of a side surface of the lightingportion in contact with the void portion functioning as a reflectivesurface which reflects light entering the lighting portion, the lightingmember having a function of, if a virtual straight line F that passesthrough a point C, at which any one light beam of the light entering thelighting portion is incident on the reflective surface, and isorthogonal to the first surface of the first base material marks aboundary between two spaces, a space with the light beam incident on thepoint C of the two spaces is labeled as a first space, and a spacewithout the light beam, incident on the point C is labeled as a secondspace, decreasing intensity of light traveling toward the second spaceof light emitted from the first base material or the lighting portion,includes arranging the lighting member such that the side surface of thelighting portion functioning as the reflective surface faces downward ina vertical direction and installing the lighting member at an upperportion of a window.

Advantageous Effects of Invention

According to one aspect of the present invention, a lighting member, alighting device, and a method for installing the lighting member capableof inexpensively suppressing glare.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view showing a lighting film according to afirst embodiment of the present invention.

FIG. 2 is a perspective view showing a lighting film according to asecond embodiment of the present invention.

FIG. 3 is a plan view showing a first modification of the lighting filmaccording to the second embodiment.

FIG. 4 is a plan view showing a second modification of the lighting filmaccording to the second embodiment.

FIG. 5 is a cross-sectional view showing a lighting film according to athird embodiment of the present invention.

FIG. 6 is a cross-sectional view showing a lighting film according to afourth embodiment of the present invention.

FIG. 7 is a cross-sectional view showing a lighting device according toa fifth embodiment of the present invention.

FIG. 8 is a perspective view showing a lighting device according to asixth embodiment of the present invention.

FIG. 9 is a cross-sectional view of the interior of a room as an exampleat the time of calculating an index of glare.

FIG. 10 is a view showing a model of a lighting film used forcalculation.

FIG. 11 is a figure showing a result of simulating a brightnessdistribution using a model without a scattering function.

FIG. 12 is a figure showing a result of simulating a brightnessdistribution using a model with an isotropic scattering function.

FIG. 13 is a figure showing a result of simulating a brightnessdistribution using a model with an anisotropic scattering function.

FIG. 14 is a view showing a room model 2000 including a lightingapparatus and an illumination dimming system.

FIG. 15 is a plan view showing a ceiling of the room model 2000.

FIG. 16 is a graph showing a relationship between illuminance given bylight (natural light) let into a room by a lighting apparatus andilluminance (the illumination dimming system) given by interiorillumination apparatuses.

DESCRIPTION OF EMBODIMENTS

[First Embodiment]

A first embodiment of the present invention will be described below withreference to FIG. 1.

A lighting film according to the first embodiment is one example of alighting member which lets sunlight into a room, for example, in a formattached to a window.

FIG. 1 is a cross-sectional view showing the lighting film according tothe present embodiment.

Note that, in each of the drawings below, constituent elements areillustrated on different dimensional scales to increase the visibilityof each constituent element.

As shown in FIG. 1, a lighting film 1 according to the presentembodiment includes a first base material 2, a plurality of lightingportions 3, a first bonding layer 4, a second base material 5, a secondbonding layer 6, and a light scattering layer 7. The plurality oflighting portions 3 are provided on a first surface 2 a of the firstbase material 2. The second base material 5 is arranged so as to facethe first surface 2 a of the first base material 2 across the pluralityof lighting portions 3. A first surface 5 a of the second base material5 and the plurality of lighting portions 3 are bonded together by thefirst bonding layer 4. The light scattering layer 7 is provided on asecond surface 2 b of the first base material 2. The second bondinglayer 6 is provided on a second surface 5 b of the second base material5 and plays a role in bonding the whole of the lighting film 1 to awindowpane 8. Clearances between the plurality of lighting portions 3constitute void portions 9.

As the first base material 2, an optically transparent base materialmade of, for example, a thermoplastic polymer or a resin, such as athermosetting resin or a photopolymerizable resin. An opticallytransparent base material made of, for example, an acrylic polymer, anolefin-based polymer, a vinyl-based polymer, a cellulose-based polymer,an amid-based polymer, a fluorinated polymer, a urethane-based polymer,a silicone-based polymer, or an imide-based polymer is used. Morespecifically, an optically transparent base material, such as atriacetylcellulose (TAC) film, a polyethylene terephthalate (PET) film,a cycloolefin polymer (COP) film, a polycarbonate (PC) film, apolyethylene naphthalate (PEN) film, a polyether sulphone (PES) film, ora polyimide (PI) film, is preferably used. In the present embodiment, aPET film with a thickness of 100 μm is used as one example. The totallight transmittance of the first base material 2 is preferably not lessthan, for example, 90%. With this configuration, sufficient transparencyis achieved.

An optically transparent base material similar to that as the first basematerial 2 is used as the second base material 5. The material for thesecond base material 5 and the material for the first base material 2may be the same or different.

The lighting portion 3 is made of an organic material having opticaltransparency and photosensitivity, such as an acryl resin, an epoxyresin, or a silicone resin. A transparent-resin mixture obtained bymixing a polymerization initiator, a coupling agent, a monomer, anorganic solvent, or the like into one of the resins can be used.Additionally, the polymerization initiator may contain variousadditional components, such as a stabilizer, an inhibitor, aplasticizer, a fluorescent brightener, a mold lubricant, a chaintransfer agent, or any other photopolymerizable monomer. The total lighttransmittance of the lighting portion 3 is preferably not less than 90%.With this configuration, sufficient transparency is achieved.

The lighting portion 3 is a member which extends long and narrowly in alinear fashion in one direction (a direction perpendicular to the sheetsurface of FIG. 1) and has a trapezoidal cross-sectional shapeorthogonal to a lengthwise direction. The lengthwise direction of thelighting portion 3 is parallel to one side of the rectangular first basematerial 2. The plurality of lighting portions 3 are arranged atintervals in parallel to one another. A surface corresponding to a shortside of two sides parallel to each other of a trapezoid forming thecross-sectional shape of the lighting portion 3 is a surface facing thesecond base material 5 and will be referred to as a first end face 3 ain the description below. A surface corresponding to a long side is asurface in contact with the first base material 2 and will be referredto as a second end face 3 b in the description below.

Let W1 be the width of the first end face 3 a of the lighting portion 3;W2 be the width of the second end face 3 b of the lighting portion 3; Hbe the height in a normal direction of the first base material 2 of thelighting portion 3; and P be the spacing in an array direction of thelighting portions 3. All the lighting portions 3 are equal in the widthW1 of the first end face 3 a, the width W2 of the second end face 3 b,the height H, and the spacing P of the lighting portions 3. Therelationship W1<W2 holds for the width W1 of the first end face 3 a andthe width W2 of the second end face 3 b. The width W1 of the first endface 3 a and the width W2 of the second end face 3 b of the lightingportion 3 are, for example, 10 μm to 50 μm. The height H of the lightingportion 3 is, for example, 10 μm to 100 μm.

Note that although an example with the plurality of lighting portions 3arranged at intervals is shown here, edges of the second end faces 3 bof the adjacent lighting portions 3 may be in contact with each other.

Air is present in the void portion 9. The refractive index of the voidportion 9 is generally 1.0. The refractive index set at 1.0 of the voidportion 9 minimizes a critical angle at an interface 3 c between thevoid portion 9 and the lighting portion 3. Although the void portion 9is an air layer made of air in the present embodiment, the void portion9 may be an inert gas layer made of an inert gas, such as nitrogen, ormay be a reduced-pressure layer-under a reduced pressure.

The light scattering layer 7 has a configuration in which lightscattering bodies 11 are dispersed in resin 10 having opticaltransparency. As the resin 10, a transparent-resin mixture obtained by,for example, mixing a polymerization initiator, a coupling agent, amonomer, an organic solvent, or the like into a resin, such as anacrylic resin, an epoxy-based resin, or a silicone-based resin can beused. The polymerization initiator may contain various additionalcomponents, such as a stabilizer, an inhibitor, a plasticizer, afluorescent brightener, a mold lubricant, a chain transfer agent, andany other photopolymerizable monomer.

The light scattering body 11 is instrumental in scattering lightentering the light scattering layer 7. The light scattering body 11 is aparticle (small piece) which has a refractive index different from thatof the resin 10 constituting the light scattering layer 7. Desirably,the light scattering bodies 11 are mixed into the light scattering layer7 and are dispersed without clumping together. For the light scatteringbody 11, an optically transparent material made of, for example, aglass, an acrylic polymer resin, an olefin-based polymer resin, avinyl-based polymer resin, a cellulose-based polymer resin, anamide-based polymer resin, a fluorinated polymer resin, a urethane-basedpolymer resin, a silicone-based polymer resin, or an imide-based polymerresin is used. Alternatively, the light scattering bodies 11 may be airbubbles dispersed in the resin 10. The shape of the light scatteringbody 11 may be, for example, a spherical shape, an oval spherical shape,a flat-plate shape or a polyhedron.

The sizes of the light scattering bodies 11 may be, for example, about0.5 to 20 μm and may be uniform or different.

The light scattering layer 7 is not limited to a configuration with thedispersed light scattering bodies 11 and may be composed of a layer withasperities on a surface. In this case, the asperities may be formeddirectly on the second surface 2 b of the first base material 2.

The first bonding layer 4 bonds the first surface 5 a of the second basematerial 5 and the first end faces 3 a of the plurality of lightingportions 3 together. For the first bonding layer 4, a common opticaladhesive is used. The refractive index of the first bonding layer 4 isdesirably equal to that of the second base material 5 or that of thelighting portion 3. If the refractive index of the first bonding layer 4is equal to that of the second base material 5 or that of the lightingportion 3, refraction does not occur at an interface between the firstbonding layer 4 and the second base material 5 or an interface betweenthe first bonding layer 4 and the lighting portion 3.

The second bonding layer 6 bonds the second surface 5 b of the secondbase material 5 and the windowpane 8 together. The second bonding layer6 may be initially provided as a constituent element of the lightingfilm 1 on the second surface 5 b of the second base material 5 or maynot be provided. If the second bonding layer 6 is not provided, thesecond bonding layer 6 may be supplied to the second surface 5 b of thesecond base material 5 at the time of the work of attaching the lightingfilm 1 to the windowpane 8. For the second bonding layer 6, a commonoptical adhesive is used. The refractive index of the second bondinglayer 6 is desirably equal to that of the second base material 5 or thatof the windowpane 8. If the refractive index of the second bonding layer6 is equal to that of the second base material 5 or that of thewindowpane 8, refraction does not occur at an interface between thesecond bonding layer 6 and the second base material 5 or an interfacebetween the second bonding layer 6 and the windowpane 8.

The lighting film 1 is attached to the windowpane 8 such that thelengthwise direction of the lighting portion 3 corresponds to ahorizontal direction while the array direction of the plurality oflighting portions 3 corresponds to a vertical direction. Light reachingdirectly from the sun enters the lighting film 1 installed on thewindowpane 8 obliquely from above. The light entering the lighting film1 passes through the windowpane 8, the second bonding layer 6, thesecond base material 5, and the first bonding layer 4 and reaches thelighting portion 3.

For convenience of explanation, a point at which one given light ray oflight entering the lighting portions 3 is incident on the lower sidesurface 3 c (a reflective surface) of the lighting portion 3 is labeledas a point C. A virtual straight line which passes through the point Cand is orthogonal to the first surface 2 a of the first base material 2is labeled as a straight line F. A space with light incident on thepoint C of two spaces with a horizontal plane including the straightline F as a boundary is labeled as a first space S1, and a space withoutthe light incident on the point C is labeled as a second space S2.

Light L1 entering from the first end face 3 a of the lighting portion 3is totally reflected at, for example, the lower side surface 3 c of thelighting portion 3, travels obliquely upward, that is, toward the firstspace S1, and is emitted from the lighting portion 3.

The light L1 emitted from the lighting portion 3 passes through thefirst base material 2, is scattered by the light scattering body 11 ofthe light scattering layer 7, and is emitted from the lighting film 1.Light L2 entering from the first bonding layer 4 on an upper sidesurface 3 d of the lighting portion 3 through the void portion 9 enters,for example, the lower side surface 3 c of the lighting portion 3 at anangle less than the critical angle. The light L2 is not reflected at thelower side surface 3 c of the lighting portion 3, travels obliquelydownward, that is, toward the second space S2, and is emitted from, thelighting portion 3. The light L2 emitted from the lighting portion 3 isscattered by the light scattering body 11 of the light scattering layer7 arid is emitted from the lighting film 1.

Like the light L2 shown in FIG. 1, light which is emitted from thelighting film 1 and travels obliquely downward may reach the position ofeyes of a person present in a room, that is, a so-called glare region todazzle the person in the room. The glare region is a region defined onthe basis of the position of eyes in a region where a person moves. Morespecifically, the glare region is a region which is, for example, 1 m ormore away from a window-side wall and is a space region at a height of,for example, about 0.8 m to 1.8 m from a floor. Even in a case where theinterior of a room is well illuminated with light traveling toward aceiling, a person present in the room is likely to feel discomfort if alarge quantity of light reaches the glare region.

In contrast, in the lighting film 1 according to the present embodiment,since the light scattering layer 7 is provided on a light emitting sideof the first base material 2, light emitted from the first base material2 is scattered by the light scattering layer 7 and decreases inintensity of light. For this reason, the intensity of light travelingobliquely downward from the lighting film 1 is lower than in a casewithout the light scattering layer 7, and a person present in a room isunlikely to be dazzled. The intensity of light traveling obliquelyupward from the lighting film 1 is slightly lower. Since the light isscattered by the light scattering layer 7, an intensity distribution ishomogenized, and a ceiling and wall surfaces in the room are morehomogenously illuminated.

As described above, the lighting film 1 according to the presentembodiment is capable of suppressing glare only by including the lightscattering layer 7. The lighting film 1 can enhance comfort in a room atlower cost than a conventional technique which mechanically adjusts theopening degree of a blind.

Although colorless and transparent members are used as the first basematerial 2, the second base material 5, and the lighting portions 3 inthe present embodiment, the colors of the first base material 10, thesecond base material 5, and the lighting portions 3 are not limited tothis. For example, the first base material 2, the second base material5, and the lighting portions 3 may be colored with, for example, a paleyellow, a pale orange, or a pale blue to adjust the color temperature oflight to be let into a building. In light of designability and the like,some or all of the first base material 2, the second base material 5,and the lighting portions 3 may be colored with red, blue, or the like.This allows provision of a window like stained glass.

Although the lighting portion 3 is constructed as a member like a stripewith a fixed width in the present embodiment, the shape of the lightingportion 3 is not limited to this. If the plurality of lighting portions3 have respective lengthwise directions in generally one direction andare arranged such that the lengthwise directions are parallel to oneside of the first base material 2 with a rectangular shape, the sameworking effect as that of the present embodiment can be obtained. Theexpression “the plurality of lighting portions have respectivelengthwise directions in generally one direction”means, for example, thecase below. Light which diffuses isotropically, such as fluorescence, ismade to enter into the first base material 2 from a side opposite to aside where the lighting portions 3 of the first base material 2 areformed, and a polar-angle brightness distribution of light emitted tooutside the plurality of lighting portions 3 is measured. If a directionin which the brightness of light emitted from the plurality of lightingportions 3 is relatively high and a direction in which the brightness isrelatively low are present, the expression “the lighting portions havethe lengthwise directions in generally one direction” is used. Adirection orthogonal to the direction, in which the brightness isrelatively high, is defined as the “one direction”.

Although the intervals between the lighting portions 3 are fixed in thepresent embodiment, the intervals between the lighting portions 3 neednot be fixed. The plurality of lighting portions 3 may be arranged atirregular intervals adjacent to one another.

This configuration allows suppression of production of interferencefringes which are produced if the lighting portions 3 are regularlyformed. The plurality of lighting portions 3 need not be arranged atintervals, and adjacent ones of lighting portions 3 may be in contactwith each other.

[Second Embodiment]

A second embodiment of the present invention will be described belowwith reference to FIG. 2.

A lighting film according to the present embodiment is the same in basicconfiguration as that in the first embodiment and is different only inthe configuration of a first base material.

FIG. 2 is a perspective view showing the lighting film according to thepresent embodiment.

In FIG. 2, the same constituent elements as those in the drawing used inthe first embodiment are denoted by the same reference characters, and adescription thereof will be omitted.

The lighting film 1 according to the first embodiment isotropicallyscatters light which is emitted from the first base material 2 in alldirections. In contrast, a lighting film 21 according to the secondembodiment anisotropically scatters light which is emitted from a firstbase material 2. In particular, the lighting film 21 according to thesecond embodiment strongly scatters light emitted from the first basematerial 22 in a horizontal direction.

As shown in FIG. 2, in the lighting film 21 according to the presentembodiment, a plurality of convex lenses 23 which extend in a verticaldirection and are parallel to one another are provided on a secondsurface of the first base material 22. In other words, a lenticular lensis provided on the second surface of the first base material 22. Thesecond surface itself of the first base material 22 may be processedsuch that the convex lenses 23 are integral with the first base material22. Alternatively, the convex lenses 23 may be separate from the firstbase material 22. The lighting film 21 according to the presentembodiment does not include the light scattering layer 7 according tothe first embodiment. Other constituent elements are the same as thosein the first embodiment.

A lens surface of the convex lens 23 has a curvature in a horizontalplane but has no curvature in the vertical direction. The convex lens 23has high light scattering ability in the horizontal direction and has nolight scattering ability in the vertical direction. Thus, light Lentering the first base material 22 from a lighting portion 3 is widelyscattered in the horizontal direction when the light L is emitted fromthe convex lens 23 and is emitted without being scattered in thevertical direction while maintaining an angular distribution when thelight L is emitted from the lighting portion 3. For this reason, thelighting film 21 according to the present embodiment is capable ofsuppressing glare without changing irradiation performance in a depthdirection of a room.

Additionally, the lighting film 21 according to the present embodimentcauses the light L emitted from the first base material 22 to bescattered in the horizontal direction and is thus capable of moderatinga change in the irradiation performance associated with, for example, anazimuthal variation due to diurnal motion of the sun. This allowsenhancement of the uniformity ratio in the horizontal direction of thelighting film 21.

Note that although the plurality of convex lenses 23 are provided on thesecond surface of the first base material 22 in the present embodiment,an anisotropic scatter structure may be provided on the second surfaceof the first base material instead. As the anisotropic scatterstructure, a structure with asperities on the order of μm in a surfacerelief holographic pattern like, for example, a light diffusion controlfilm (trade name: LSD) from Luminit, LLC can be used. Alternatively, alight scattering layer obtained by dispersing particles with aspectratios of about 5 to 500 in a continuous layer may be used on the secondsurface of the first base material instead of an uneven structure.

[First Modification of Second Embodiment]

A lighting film 25 shown in FIG. 3 may be used instead of a lightingfilm including a plurality of lighting portions extending linearly.

In the lighting film 25 according to a first modification, a pluralityof tiling regions TA1 and TA2 are provided on a second surface of afirst base material 26, as shown in FIG. 3. In each of the plurality oftiling regions TA1 and TA2, a plurality of arc-like lighting portions 28which are concentrically arranged as viewed from a normal direction ofthe first base material 26 are formed. The two adjacent tiling regionsTA1 and TA2 are identical in the shapes of the lighting portions 28 inthe tiling region but are different in a direction in which arcs areconvex from each other.

In the present embodiment, the plurality of tiling regions TA1 and TA2include two types of tiling regions. The first tiling region TA1 and thesecond tiling region TA2 each have the shape of a quadrangle. Morespecifically, the quadrangle has two sets of two adjacent sides of equallength. In the present embodiment, a quadrangle with four internalangles of 120°, 90°, 60°, and 90° is adopted.

In each of the first tiling region TA1 and the second tiling region TA2,a plurality of (six in the present embodiment) concentric lightingportions 28 about a vertex with an internal angle of 60° are formed. Thecross-sectional shape of the lighting portion 28 is a trapezoidal shapewith the area of a light emitting end face larger than the area of alight incoming end face. In the first base material 26, a plurality oflighting portions 28 equal in cross-sectional shape are concentricallyarranged at fixed intervals.

The shapes of the first tiling region TA1 and the second tiling regionTA2 are the same except that the shapes are vertically reverse to eachother such that the shapes are opposite in a direction in which arcs areconvex. The first tiling regions TA1 and the second tiling regions TA2are arranged on one surface of the first base material 26 without anyclearance between the tiling regions.

In the lighting film 25 according to the first modification, thelighting portion 28 is curved, and an extending direction of thelighting portion 28 varies in one tiling region TA1 or TA2. Thisconfiguration causes light emitted from the lighting portion 28 to bescattered in a horizontal direction and allows suppression of glare.Like the above-described embodiment, the uniformity ratio in thehorizontal direction of the lighting film 25 can be enhanced.

[Second Modification of Second Embodiment]

A lighting film 31 shown in FIG. 4 may be used instead of a lightingfilm including a plurality of lighting portions extending like stripes.

As shown in FIG. 4, in the lighting film 31 according to a secondmodification, a first base material 32 includes a plurality of lightingportions 33 with the shapes of truncated elliptical cones. Although thedimensions of the plurality of lighting portions 33 are different in theexample in FIG. 4, the dimensions may be the same. The plurality oflighting portions 33 are randomly arranged but may be regularlyarranged. In either case, the plurality of lighting portions 33 arearranged with a major axis direction of an ellipse forming a contour ofeach lighting portion 33 facing in a horizontal direction and a minoraxis direction of the ellipse facing in a vertical direction when theplurality of lighting portions 33 are viewed from a normal direction ofthe first base material 32.

In the lighting film 31 according to the second modification, the planarshape of the lighting portion 33 is an elliptical shape, and areflective surface of the lighting portion 33 is curved. Thisconfiguration causes light emitted from the lighting portion 33 to bescattered in the horizontal direction and allows suppression of glare.Additionally, the uniformity ratio in the horizontal direction of thelighting film 31 can be enhanced, like the above-described embodiment.

[Third Embodiment]

A third embodiment of the present invention will be described below withreference to FIG. 5.

A lighting film according to the present embodiment is the same in basicconfiguration as that in the first embodiment and is different only inthe configuration of a first base material.

FIG. 5 is a cross-sectional view showing the lighting film according tothe present embodiment.

In FIG. 5, the same constituent elements as those in the drawing used inthe first embodiment are denoted by the same reference characters, and adescription thereof will be omitted.

A lighting film 35 according to the third embodiment anisotropicallyscatters light emitted from a first base material 36, as in the secondembodiment. Note that, in contrast to the lighting film 21 according tothe second embodiment that strongly scatters light emitted from thefirst base material 22 in the horizontal direction, the lighting film 35according to the third embodiment strongly scatters light headingobliquely downward of light emitted from the first base material 36.

As shown in FIG. 5, in the lighting film 35 according to the presentembodiment, the first base material 36 contains a plurality of minutepieces 37 having a refractive index different from that of the firstbase material 36.

The minute piece 37 is a rod-like or plate-like minute particle having alengthwise direction and a widthwise direction. The plurality of minutepieces 37 are oriented such that the lengthwise direction facesgenerally obliquely downward. If the first base material 36 contains theminute piece 37 of this type, light L2 traveling along the lengthwisedirection of the minute piece 37 is scattered due to the action of theminute piece 37.

In contrast, light L1 traveling along a direction which intersects thelengthwise direction of the minute piece 37 passes without beingaffected by the minute pieces 37. That is, the first base material 36has an anisotropic scattering function of selectively and stronglyscattering light-heading obliquely downward. Note that a film having afunction of scattering light heading obliquely downward, such as ananisotropic scattering film like, for example, Lumisty (which is a tradename and is manufactured by Sumitomo Chemical Company, Limited) may beattached to a second surface of the first base material, instead of theconfiguration, in which the first base material 36 contains theplurality of minute pieces 37. The lighting film 35 according to thepresent embodiment does not include the light scattering layer 7according to the first embodiment. Other constituent elements are thesame as those in the first embodiment.

The lighting film 35 according to the present embodiment has high lightscattering ability for light heading obliquely downward and has no lightscattering ability for light heading upward. For this reason, use of thelighting film 35 according to the present embodiment allows suppressionof glare without changing irradiation performance in a direction towarda room ceiling.

[Fourth Embodiment]

A fourth embodiment of the present invention will be described belowwith reference to FIG. 6.

A lighting film according to the fourth embodiment is the same in basicconfiguration as that in the first embodiment and is different from thefirst embodiment in that a louver is added to a first base material.

FIG. 6 is a cross-sectional view showing the lighting film according tothe fourth embodiment.

In FIG. 6, the same constituent elements as those in the drawing used inthe first embodiment are denoted by the same reference characters, and adescription thereof will be omitted.

As shown in FIG. 6, a lighting film 41 according to the presentembodiment has a louver 42 which is provided on a second surface 2 b ofa first base material 2. The louver 42 is composed of a plurality ofelongated rectangular plate materials 43 (light absorbing members). Anextending direction of the plurality of plate materials 43 is parallelto an extending direction of the lighting portions 3 (a directionperpendicular to the sheet surface of FIG. 6). A lower end of the platematerial 43 is fixed to the second surface 2 b of the first basematerial 2, and an upper end side of the plate material 43 extendsobliquely upward from the lower end. That is, an angle α which thesecond surface 2 b of the first base material 2 forms with an uppersurface 43 a of the plate material 43 is an acute angle less than 90°.Of two surfaces of the plate material 43, at least the upper surface 43a is, for example, black and has light absorbency. Additionally, a lowersurface 43 b of the plate material 43 may have light absorbency.

Light L1 reflected at a lower side surface 3 c of the lighting portion 3travels obliquely upward and is unlikely to hit the obliquely arrangedplate material 43. Thus, the light L1 travels in a direction toward aceiling without significantly changing a traveling direction. Incontrast, light L2 emitted in a direction close to a horizontaldirection or obliquely downward from the first base material 2 hits theupper surface 43 a of the plate material 43 and is absorbed by the uppersurface 43 a. For this reason, the light L2 traveling in the directionclose to the horizontal direction or obliquely downward decreases inintensity. As described above, the lighting film 41 according to thepresent embodiment allows suppression of glare without significantlychanging irradiation performance in the direction toward the roomceiling. An angular range for the light L1 that passes through thelighting film 41 can be adjusted by changing the angle α which the firstbase material 2 forms with the plate material 43 and the dimensions ofthe plate material 43.

In the present embodiment, the plate material 43 is configured such thatthe surfaces have light absorbency. Instead of this, the surfaces of theplate material may have light reflectiveness. If a plate material (lightreflecting member) having light reflectiveness is used, light emittedfrom the first base material in a direction close to the horizontaldirection or obliquely downward is reflected at an upper surface of theplate material and heads upward. With this configuration, it is possibleto enhance the brightness of a room while suppressing glare. Note thatreflection on a surface of a plate material is desirably diffusereflection. This is because, if reflection on a surface of a platematerial is specular reflection, intense reflective light may traveldownward to cause glare. In that context, if a plate material has lightreflectiveness, only an upper surface of the plate material desirablyhas light reflectiveness. Alternatively, an upper surface of a platematerial may have light reflectiveness, and a lower surface of the platematerial may have light absorbency.

[Fifth Embodiment]

A fifth embodiment of the present invention will be described below withreference to FIG. 7.

A lighting device according to the fifth embodiment includes the samelighting film as that in the first embodiment.

FIG. 7 is a cross-sectional view showing the lighting device accordingto the fifth embodiment.

In FIG. 7, the same constituent elements as those in the drawing used inthe first embodiment are denoted by the same reference characters, and adescription thereof will be omitted.

As shown in FIG. 7, a lighting device 45 according to the presentembodiment includes a lighting film 46 and a blind 47 (a lightattenuating member). Although the configuration of the lighting film 46is the same as that in the first embodiment, the lighting film 46according to the present embodiment does not include the lightscattering layer 7. In the present embodiment, the blind 47 plays afunction of suppressing glare. The blind 47 includes a plurality ofslats 48, a ladder cord 49, and a support member 50. The slat 48 is anelongated plate material having light absorbency or light scatteringability, and the slats 48 are configured such that the angle thereof ischanged by operating the ladder cord 49. The plurality of slats 48 andthe ladder cord 49 are supported by the support member 50.

As in the fourth embodiment, the lighting device 45 according to thepresent embodiment can cause light L2 traveling in a direction close toa horizontal direction or obliquely downward to decrease in intensitywithout greatly affecting light L1 heading obliquely upward by adjustingthe angle of the plurality of slats 48 such that the slats 48 face in amoblique direction. Thus, the lighting device 45 according to the presentembodiment can suppress glare without significantly changing irradiationperformance in a direction toward a room ceiling. An angular range forlight which passes through the lighting device 45 can be adjusted bychanging the angle of the slats 48 of the blind 47.

[Sixth Embodiment]

A sixth embodiment of the present invention will be described below withreference to FIG. 8.

A lighting device according to the sixth embodiment includes the samelighting film as that in the first embodiment.

FIG. 8 is a cross-sectional view showing the lighting device accordingto the sixth embodiment.

In FIG. 8, the same constituent elements as those in the drawing used inthe first embodiment are denoted by the same reference numerals, and adescription thereof will be omitted.

As shown in FIG. 8, a lighting device 55 according to the presentembodiment includes a rolling screen 56 and a lighting film 57. Anopening portion (not shown) is formed in part of a light shielding cloth58 constituting the rolling screen 56, and the lighting film 57 as thatin the first embodiment is built in at the position of the openingportion. For example, if one side of a 2.7-m-high room, constitutes awindow, and the length of the light shielding cloth 58 when the rollingscreen 56 is stretched to the utmost limit is approximately 2.7 m, thelighting film 57 is arranged at a height of more than 1.8 m from a floorsurface. That is, the lighting film 57 is arranged at a height generallygreater than a line of sight of a person present in the room.

In the lighting device 55 according to the present embodiment, thelighting film 57 is arranged at a high height, which allows moreeffective suppression of glare. Since a lower portion of the window iscovered with the light shielding cloth 58, the privacy of the room canbe protected.

The example of the lighting device 55, in which the lighting film 57 isbuilt in part of the rolling screen 56, has been illustrated. Even in acase where the lighting film is attached directly to the window, as inthe first embodiment, an installation method that arranges the lightingfilm such that a lower side surface of a lighting portion faces downwardin a vertical direction and attaches the lighting film to only an upperportion of the window may be adopted. With the adoption, it is possibleto effectively suppress glare while securing lighting performance for aroom ceiling to some extent.

Note that the technical scope of the present invention is not limited tothe above-described embodiments and that various changes may be madewithout departing from the spirit of the present invention. For example,the first embodiment has illustrated a case where a light scatteringlayer is provided on an outer side of a second surface of a first basematerial. However, any member among a first base material, a lightingportion, a first bonding layer, a second base material, and a secondbonding layer may be provided with light scattering ability using amethod, such as mixing minute particles different in refractive indexinto the member. Note that it is more desirable in terms of minimizingeffects on ceiling irradiation performance to provide a member closer toa light emitting side with light scattering ability.

The above-described embodiments have each illustrated a case where lightis made incident from a first end face, that is, an end face with asmaller area of a lighting portion. In contrast, light may be madeincident from a second end face, that is, an end face with a larger areaof a lighting portion. Additionally, the cross-sectional shape of alighting portion is not limited to a trapezoid. The shape may be aquadrangle or a triangle other than a trapezoid, and one of othervarious shapes may be adopted. In addition, a specific configuration,such as a material, a shape, and dimensions, of each constituent elementillustrated in the embodiments may be appropriately changed.

EXAMPLES

Glare is divided into disability glare which refers to a phenomenon inwhich a high-intensity light source close to a line of sight makes avisual object less invisible and discomfort glare which causespsychological discomfort. Since general offices are less likely to havea light source which may cause disability glare, emphasis is placed onmeasures against discomfort glare. Discomfort glare can bequantitatively expressed on the basis of the luminance of a lightsource, the size of the light source, the position of the light source,or the brightness of the background, such as a ceiling surface or a wallsurface. One of indexes of discomfort glare is the unified glare rating(UGR) as a standard adopted by the International Commission onIllumination (CIE).

Letting Lb [cd/m²] be background luminance; L [cd/m²] be the luminance;of a light emitting portion of illumination with respect to a directionof eyes of an observer; ω [sr] be the solid angle of the light emittingportion of the illumination in a field of view of the observer; and P bethe position index of the illumination, UGR is represented by Expression(1) below:UGR=8×log {(0.25/Lb)×Σ(L ² ω/P ²)}  (1)

The present inventors demonstrated a glare-reduction effect of alighting film according to the present embodiment by a simulation usingUGR described above. A result of the simulation will be described below.

As shown in FIG. 9, a south-facing room 14 with a depth w of 16 m wastaken as a simulation condition. A window 15 at a fixed height wasarranged on the south side of the room 14, and a lighting film 16 wasinstalled so as to cover an upper third of the window 15. Specifically,a height from a floor surface to a ceiling of the room 14 was set at 2.7m, a height T1 from a lower end of the window 15 to an upper end (theceiling) was set at 1.8 m, and a height T2 from the floor surface to thelower end of the window 15 was set at 0.9 m. A dimension T3 in a heightdirection of the lighting film 16 was set at 0.6 m, and an upper end ofthe lighting film 16 was aligned with the upper end of the window 15.The culmination altitude of the sun was set at 55°.

As to the quantity of sunlight, horizontal direct solar irradiance wasset at 2.37 MJ/m²/h, and horizontal diffuse solar irradiance was set at0.62 MJ/m²/h. These solar irradiances each correspond to solarirradiance in Tokyo at 12 a.m. on March 16 in average year. Each solarirradiance on a horizontal plane was converted into solar irradiance ona window surface. Window direct solar irradiance was 50849 lm/m², andwindow diffuse solar irradiance was 9499 lm/m².

As to the intensity of sunlight, the apparent diameter of the suncorresponding to spread of direct solar radiation light was set at 0.52deg., and a light source for direct solar radiation, having a distance dof 1.5×10⁸ km and a radius r of 7×10⁵ km, which re-created the apparentdiameter was prepared. A uniform-intensity light source for diffusesolar radiation was also separately prepared.

An observation position X1 for calculating UGR was set at a position 8 mfrom the window at the center of the room. At the position 8 m from thewindow, UGR was calculated for three types of models, a model accordingto a comparative example in which a lighting film had no lightscattering ability, a model according to Example 1 in which a lightingfilm had isotropic scattering, and a model according to Example 2 inwhich a lighting film had anisotropic scattering. As a calculationcondition common, to the three types of models, a lighting film shown inFIG. 10 was taken. A width W1 of a first end face of a lighting portion3A was set at 13.4 μm, and a width W2 of a second end face was set at 30μm. A height H of the lighting portion 3A was set at 45 μm.

The model according to Example 1 was set such that isotropic Gaussianscattering, having a standard deviation of 15° for a brightnessdistribution at the time of scattering parallel light, was imparted to alight emitting surface. The model according to Example 2 was set suchthat anisotropic Gaussian scattering, having a standard deviation of 5°in a vertical direction and a standard deviation of 60° in a horizontaldirection for a brightness distribution at the time of scatteringparallel light, was imparted to a light emitting surface. Note that, atthe time of UGR calculation, UGR was calculated while dividing thewindow and regarding the window as a collection of small light sources.

FIG. 11 is a figure showing a brightness distribution at a lightingsurface in the model according to the comparative example. In anupper-left brightness distribution chart, the abscissa represents anangle [°] in a horizontal direction while the ordinate represents anangle [°] in a vertical direction. A lower-left graph is a graph of abrightness distribution in the horizontal direction, and an upper-rightgraph is a graph of a brightness distribution in the vertical direction.

As a result of calculating UGR for the model according to thecomparative example, UGR at the position 8 m from the window was 40.1.An observer feels more discomfort with glare with an increase in thevalue of UGR and feels less discomfort with glare with a decrease in thevalue of UGR. According to a criterion for a general office, UGR isrequired to be not more than 19. Thus, the value of UGR for the modelaccording to the comparative example at the position 8 m from the windowgreatly exceeds the criterion for a general office. This is estimated tobe attributed to discomfort glare due to direct solar radiation like thelight L2 shown in FIG. 1.

FIG. 12 is a figure showing a brightness distribution at a lightingsurface in the model according to Example 1. In an upper-left brightnessdistribution chart, the abscissa represents an angle [°] in thehorizontal direction while the ordinate represents an angle [°] in thevertical direction. A lower-left graph is a graph of a brightnessdistribution in the horizontal direction, and an upper-right graph is agraph of a brightness distribution in the vertical direction. Sinceisotropic scattering was imparted to the lighting film, maximumluminance was much lower than that in the model according to thecomparative example.

As a result of calculating UGR for the model according to Example 1, thevalue of UGR at the position 8 m from the window was 18.5, whichexhibited a large improvement over 40.1 that was the value of UGR forthe model according to the comparative example.

The model according to Example 1 meets the criterion for a generaloffice. As described above, it has been demonstrated that impartment ofisotropic scattering to a lighting film allows suppression of glare.

FIG. 13 is a figure showing a brightness distribution at a lightingsurface in the model according to Example 2. In an upper-left brightnessdistribution chart, the abscissa represents an angle [°] in thehorizontal direction while the ordinate represents an angle [°] in thevertical direction. A lower-left graph is a graph of a brightnessdistribution in the horizontal direction, and an upper-right graph is agraph of a brightness distribution in the vertical direction. Sinceanisotropic scattering was imparted to the lighting film, maximumluminance was much lower than that in the model according to thecomparative example.

As a result of calculating UGR for the model according to Example 2, thevalue of UGR at the position 8 m from the window was 18.3, whichexhibited a large improvement over 40.1 that was the value of UGR forthe model according to the comparative example.

The model according to Example 2 meets the criterion for a generaloffice. As described above, it has been demonstrated that impartment ofanisotropic scattering to a lighting film allows suppression of glare.It has been found that impartment of anisotropic scattering having highscattering ability, particularly in the horizontal direction, to alighting film allows a reduction in glare without largely affecting aceiling illuminance distribution.

Note that the calculated UGR values are illustrative only and that theUGR value for the model according to each example can be optimized by,for example, appropriately changing the shape of a lighting portion andthe level of light scattering ability.

[Illumination Dimming System]

FIG. 14 is a view showing a room model 2000 including a lightingapparatus and an illumination dimming system.

FIG. 15 is a plan view showing a ceiling of the room model 2000.

In the present invention, a constituent ceiling material for a ceiling2003 a of a room 2003 which lets outside light be introduced may havehigh light reflectiveness. As shown in FIGS. 14 and 15, an opticallyreflective ceiling member 2003A is installed as a ceiling materialhaving light reflectiveness on the ceiling 2003 a of the room 2003. Theoptically reflective ceiling member 2003A is intended to promoteintroduction of outside light from a lighting apparatus 2010, which isinstalled on a window 2002, into the back of the room and is installedon a window-side portion of the ceiling 2003 a. Specifically, theoptically reflective ceiling member 2003A is installed in apredetermined region E (a region about 3 m wide extending from thewindow 2002) of the ceiling 2003 a.

As described earlier, the optically reflective ceiling member 2003Afunctions to effectively guide outside light introduced into the roomvia the window 2002, on which the lighting apparatus 2010 according tothe present invention (a lighting apparatus according to any of theabove-described embodiments) is installed, into the back of the room.Outside light introduced from the lighting apparatus 2010 toward theceiling 2003 a in the room is reflected at the optically reflectiveceiling member 2003A, turns, and illuminates a desk upper surface 2005 aof a desk 2005 which is placed at the back of the room. The opticallyreflective ceiling member 2003A exerts the effect of brightening thedesk upper surface 2005 a.

The optically reflective ceiling member 2003A may have diffusereflectiveness or specular reflectiveness. The optically reflectiveceiling member 2003A preferably has an appropriate mixture of theproperties to juggle the effect of brightening the desk upper surface2005 a of the desk 2005 placed at the back of the room and the effect ofsuppressing glare light uncomfortable for a person present in the room.

Most of light introduced into the room by the lighting apparatus 2010according to the present invention heads toward a portion near thewindow 2002 of the ceiling. The quantity of light is often sufficient inthe vicinity of the window 2002. For this reason, part of light incidenton the portion near the window (the region E) of the ceiling can bedistributed to the back of the room that is smaller in light quantitythan the window side through concurrent use of the optically reflectiveceiling member 2003A as described above.

The optically reflective ceiling member 2003A can be prepared by, forexample, embossing a metal plate of, for example, aluminum, withasperities about several tens of micrometers deep or evaporating a thinmetal film of, for example, aluminum onto a surface of a resin substratewith similar asperities. Alternatively, asperities formed throughembossing may be formed to have a longer-period curved surface.

A light distribution characteristic and a light distribution in the roomcan be controlled by appropriately changing the shape of an embossedpattern to be formed at the optically reflective ceiling member 2003A.For example, if the optically reflective ceiling member 2003A isembossed like stripes extending at the back of the room, light reflectedat the optically reflective ceiling member 2003A spreads in a left-rightdirection of the window 2002 (a direction intersecting a lengthwisedirection of asperities). In a case where the size and orientation ofthe window 2002 of the room 2003 are limited, the above-describedproperty can be used to spread light in a horizontal direction by theoptically reflective ceiling member 2003A and reflect the light in adirection toward the back of the room.

The lighting apparatus 2010 according to the present invention is usedas part of an illumination dimming system of the room 2003. Theillumination dimming system is composed of constituent members acrossthe room including, for example, the lighting apparatus 2010, aplurality of interior illumination apparatuses 2007, a solar radiationadjustment apparatus 2008 which is installed on the window, a controlsystem 2009 for these components, and the optically reflective ceilingmember 2003A installed on the ceiling 2003 a.

At the window 2002 of the room 2003, the lighting apparatus 2010 isinstalled on an upper side while the solar radiation adjustmentapparatus 2008 is installed on a lower side. Although a blind isinstalled as the solar radiation adjustment apparatus 2008 here, thepresent invention is not limited to this.

In the room 2003, the plurality of interior illumination apparatuses2007 are arranged in a grid pattern in the left-right direction (a Ydirection) of the window 2002 and in a depth direction (an X direction)of the room. The plurality of interior illumination apparatuses 2007together with the lighting apparatus 2010 constitute an illuminationsystem for the whole of the room 2003.

As shown in FIGS. 14 and 15, for example, the ceiling 2003 a of anoffice having a length L1 in the left-right direction (Y direction) ofthe window 2002 of 18 m and a length L2 in the depth direction (Xdirection) of the room 2003 of 9 m is shown. The interior illuminationapparatuses 2007 are arranged in a grid pattern at intervals P of 1.8 min a lateral direction (the Y direction) and in the depth direction (theX direction) of the ceiling 2003 a. More specifically, 50 interiorillumination apparatuses 2007 are arrayed with 10 rows (in the Ydirection) and 5 columns (in the X direction).

The interior illumination apparatus 2007 includes an interiorilluminator 2007 a, a brightness detection portion 2007 b, and a controlportion 2007 c. The brightness detection portion 2007 b and the controlportion 2007 c are configured to be integral with the interiorilluminator 2007 a.

The interior illumination apparatus 2007 may include a plurality ofinterior illuminators 2007 a and a plurality of brightness detectionportions 2007 b. Note that one brightness detection portion 2007 b isprovided for each interior illuminator 2007 a. The brightness detectionportion 2007 b receives reflected light from a radiated surface to beilluminated by the interior illuminator 2007 a and detects theilluminance of the radiated surface. The brightness detection portion200 b detects the illuminance of the desk upper surface 2005 a of thedesk 2005 placed in the room here.

The control portions 2007 c, one of which is provided for each interiorillumination apparatus 2007, are connected to one another. The interiorillumination apparatuses 2007 perform feedback control which adjustslight output from LED lamps of the respective interior illuminators 2007a with the control portions 2007 c connected to one another such thatthe illuminance of the desk upper surface 2005 a detected by eachbrightness detection portion 2007 b is fixed target illuminance L0 (forexample, average illuminance of 750 lx).

FIG. 16 is a graph showing a relationship between illuminance given bylight (natural light) let into the room by the lighting apparatus andilluminance (the illumination dimming system) given by the interiorillumination apparatuses.

As shown in FIG. 16, the illuminance of a desk upper surface given bythe lighting apparatus 2010 (through letting in natural light) decreaseswith an increase in the distance from the window. In contrast, if theinterior illumination apparatuses 2007 (the illumination dimming system)are installed on the ceiling in the room without installing the lightingapparatus 2010 on the window, the illuminance of a desk upper surfaceincreases with an increase in the distance from the window. It isapparent that the illuminance of a desk upper surface is higherthroughout the room in a case where the lighting apparatus 2010 and theinterior illumination apparatuses 2007 (the illumination dimming system)are concurrently used than in a case where either one of the lightingapparatus 2010 and the interior illumination apparatuses 2007 (theillumination dimming system) is used. Owing to the effect of thelighting apparatus 2010, it is brightest at the window. Brightness isseen decreasing slightly with an increase in the distance from thewindow, but approximately fixed illuminance (average illuminance of 750lx) is achieved.

As has been described above, the concurrent use of the lightingapparatus 2010 and the illumination dimming system (the interiorillumination apparatuses 2007) allows light to be delivered to the backof the room, which allows a further increase in the brightness of theroom. Thus, a more stable bright light environment can be achievedwithout being affected by a solar altitude.

INDUSTRIAL APPLICABILITY

The present invention can be used for a lighting member, a lightingdevice, and a method for installing the lighting member capable ofeffectively letting light into a space, such as the interior of a room.

REFERENCE SIGNS LIST

1, 16, 21, 25, 31, 35, 41, 46, 57 lighting film

2, 22, 32, 36 first base material

3, 28, 33 lighting portion

4 first bonding layer

5 second base material

7 light scattering layer

9 void portion

23 convex lens

43 plate material (light absorbing member)

45, 55 lighting device

47 blind (light attenuating member)

The invention claimed is:
 1. A lighting member comprising: a first basematerial having optical transparency; a plurality of lighting portionshaving optical transparency which are provided on a first surface of thefirst base material; a void portion which is provided between theplurality of lighting portions; wherein part of a side surface of atleast one of the plurality of lighting portions in contact with the voidportion reflects first light entering the plurality of lightingportions, and a plane that passes through a point, at which any onelight beam of the first light is incident on the side surface, and thatis orthogonal to the first surface marks a boundary between two spaces,and a space with the first light is labeled as a first space, and aspace without the first light is labeled as a second space; and a lightattenuating member which decreases intensity of second light traveling,from a light emitting side of the plurality of lighting portions, towardthe second space, and more strongly scatters the second light than athird light, the third light traveling, from the light emitting side ofthe plurality of lighting portions, towards the first space, the lightattenuating member being provided at the light emitting side.
 2. Thelighting member according to claim 1, wherein the light attenuatingmember reflects the second light.
 3. The lighting member according toclaim 1, wherein the light attenuating member absorbs the second light.4. The lighting member according to claim 1, wherein the first basematerial contains the light attenuating member.
 5. The lighting memberaccording to claim 4, wherein the first base material selectivelyscatters the second light.
 6. A lighting device comprising: a lightingmember comprising: a first base material having optical transparency; aplurality of lighting portions having optical transparency which areprovided on a first surface of the first base material; a void portionwhich is provided between the plurality of lighting portions; whereinpart of a side surface of at least one of the plurality of lightingportions in contact with the void portion reflects first light enteringthe plurality of lighting portions, and a plane that passes through apoint, at which any one light beam of the first light is incident on theside surface, and that is orthogonal to the first surface marks aboundary between two spaces, and a space with the first light is labeledas a first space, and a space without the first light is labeled as asecond space; and a light attenuating member which decreases intensityof second light traveling, from a light emitting side of the pluralityof lighting portions, toward the second space, and more stronglyscatters the second light than a third light, the third light traveling,from the light emitting side of the plurality of lighting portions,toward the first space, the light attenuating member being provided atthe light emitting side.